Rogerson 'double-cross fear': jury told

Former policemen Roger Rogerson and Glen McNamara came up with a "grandiose scheme" to increase to $30 million the amount demanded from Ron Medich, his murder trial has been told.

Key crown witness Fortunato "Lucky" Gattellari has told the trial Rogerson and McNamara were part of a plot to ask Medich for $15 million to buy Gattellari's silence in court.

Under cross-examination from Medich's lawyer, Winston Terracini SC, Gattellari said he came to the view that Rogerson and McNamara were going to double-cross him.

"It became very obvious to me that things were not going the way we were saying," he told the NSW Supreme Court jury on Wednesday.

The pair had come up with a "grandiose scheme of asking for $30 million", he added.

Millionaire property developer Medich, 68, is accused of directing Gattellari to organise the murder of his former business partner, Michael McGurk, who was gunned down outside his Sydney home in September 2009.

Gattellari has received a 60 per cent discount on his sentence after admitting his role in the murder and helping authorities.